ATLANTA — Children ages 6 months through 8 years who did not receive at least one dose of the 2009 influenza A(H1N1) monovalent vaccine during the 2009-2010 influenza season should receive two doses of a 2010-2011 seasonal influenza vaccine, which will include H1N1 coverage, according to a new recommendation from the Centers for Disease Control and Prevention.
Prior recommendations stated that children in this age group who received two doses in the first influenza season in which they are vaccinated require only one dose the following season.
The CDC's Advisory Committee on Immunization Practices (ACIP) voted June 24 to make this change to its existing seasonal influenza vaccination recommendations.
The recommendations continue to state that children ages 6 months through 8 years who are receiving a seasonal vaccine for the first time should receive two doses, and that those who received only one dose of a seasonal vaccine in the first influenza season in which they were vaccinated should receive two doses in the following season.
If children in this age group received at least one dose of 2009 H1N1 flu vaccine last year, they need only one dose of the seasonal vaccine in 2010-2011, provided they received two doses of seasonal flu vaccine in their first year of receiving seasonal vaccines.
The additional recommendation was made in light of immunogenicity and vaccine effectiveness data suggesting that children under age 9 years who receive only one dose of an 2009 H1N1 flu vaccine instead of the recommended two doses have reduced rates of seroconversion.
Children in that age group also have lower rates of immunity resulting from natural influenza infection.
The ACIP Influenza Vaccine Working Group, which proposed the change, reported that protective titers of hemagglutinin inhibition following a single dose of a 2009 H1N1 monovalent vaccine during the 2009 pandemic occurred in as few as 19% of children aged 6 months to 3 years, and as few as 44% of those aged 3-9 years.
Protective titers were present in at least 90% of older children and adults up to age 65 years, and in 81% of those age 65 and older.
After two doses, 73%-100% of infants and young children developed protective titers.
Disclosures: Dr. Shay said he had no conflicts of interest, and Dr. Lieu said she had none other than that the studies were funded by the CDC and FDA.
If a child aged 6 months to 8 years received at least one dose of 2009 H1N1 flu vaccine last year, he needs only one dose of the seasonal vaccine in 2010-2011, provided he received two doses of seasonal flu vaccine in his first year of receiving seasonal flu vaccine.
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